NTT Corporation (NTT) and Nokia Corporation (Nokia) demonstrated that the IOWN All Photonics Network (APN) which is considered an architecture for IOWN Global Forum, can be applied to the mobile front-haul between the antenna unit (Radio Unit/RU) and the control unit (Distributed Unit/DU) of a 5G RAN base station. In the demonstration, even when the distance between RU and DU is about 25 km, the low delay transmission using IOWN APN meets the standard regulation of mobile front-haul, and it was confirmed that the RU and DU of 5G operate normally. This achievement will contribute to reducing the number of DUs and their power consumption by enabling long-distance transmission between RU and DU and wide-range base station operation.
1. Background of the study
5G and 6G use higher frequency bands than 4G and require many base stations to cover the same area, which creates a problem of increase in the number of base stations and power consumption.
Until now, we have dealt with this problem by separating the antenna equipment and the control equipment of the base station and aggregating the DUs. The IOWN GF’s report states that the distance between RU and DU is often less than 7 km, which means that a large number of RUs that exist over a wide area cannot be sufficiently aggregated into a DU.
Conventionally, a fixed single-mode optical fiber connection (dark fiber) has been used for the mobile front-haul between the RU and DU, but in this case, the RU is connected in single mode with a specific DU, and in the event of a failure, service in the area covered by the RU is affected.
The IOWN APN enables dynamic re-routing between RUs and DUs. If a failure occurs between an RU and a DU, the IOWN APN can bypass the failure, allowing the service to continue in the area covered by the RU. There is currently a strict industry standard for mobile front-haul with a delay time of 160 μs or less, and 5G RUs and DUs are designed to operate under this standard. In this demonstration, we verified that 5G RU and DU can operate normally even if the distance between RU and DU is extended by using IOWN APN.
Figure 1 Mobile Fronthaul and Delay Requirements
2. Overview of demonstration experiments
The IOWN APN connects the 5G RUs and DUs to verify that the 5G RUs and DUs work properly for long-distance transmission, including data transfer. The verification was performed in accordance with the IOWN Global Forum's PoC Reference for the IOWN for the mobile network, including the IOWN APN device configuration and transmission method. We also tested different APN device sections (Between APN-T and APN-G, between APN-G and APN-I, etc.) for long-distance transmission, assuming various APN device deployments.
2.1. Results of demonstration experiment
As a result of the demonstration experiments, it was confirmed that RU and DU operate normally in an environment with a transmission distance of 25 km, that there is no impact on the communication quality such as data transfer speed and loss rate, and that the delay time is 133 μs.
We also confirmed in theory that, with a delay time of 133 μs, the maximum distance of long-distance transmission is approximately 30 km.
Figure 2 Structure and Results of Demonstration Experiment
2.2. Role of each company in the demonstration experiment
A mobile front-haul demonstration experiment (Figure 2) using the IOWN APN was conducted as follows:
- NTT: Conduct a demonstration experiment to provide a test environment that can confirm the health and measure the quality of 5G mobile communications such as terminals, RU, and CU/DU.
- Nokia: Provide IOWN APN devices such as Flexible Bridge, APN-T, APN-G and APN-I for the demonstration experiment.
3. Outlook
This demonstration showed that 5G RU and DU work correctly even if the distance between RU and DU is extended by using IOWN APN.
In the future, NTT will simulate the failure between RU and DU, and work on a demonstration experiment to see if stable mobile communication services can continue under those environments by dynamically re-routing the IOWN APN, with the aim of realizing a resilient network. In addition, they will work on a demonstration experiment of a power-efficient mobile network by dynamically re-routing between RUs and DUs using IOWN APN according to fluctuations in the number of users and traffic volume during the day and at night.
“I believe this is a significant achievement proving the effectiveness of the IOWN Global Forum All Photonics Network for the mobile front-haul. The result clearly illustrates the technical feasibility of a robust and flexible commercial mobile network with low power consumption. NTT will continue to collaborate with Nokia and other IOWN Global Forum members to develop the next generation of ICT infrastructures.” said Katsuhiko Kawazoe, Representative Member of the Board, Senior Executive Vice President (CTO/ CIO/ CDO), NTT.
“Nokia is proud to contribute to the IOWN GF and we are looking forward to our continued journey with NTT and other IOWN GF members. As an innovative and trusted global optical leader, Nokia is deeply aware of the growing need for high-speed and low-latency connections because of the virtualization of key mobile core components. This test showcases that our high-performance optical solutions are designed to effectively address this need.” said James Watt, Vice President and General Manager for the Optical Networks Division at Nokia.
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